Method for generating a signal for detecting the direction of movement of a laser spot, and apparatus therefor

摘要

A method and apparatus for detecting the direction of movement of a laser spot in an optical disc recording/reproducing apparatus having a photodetector divided into two or more sections, each of which is a light receiving device, aligned in a radial direction that includes detecting a phase difference between the light receiving signals corresponding to light receiving devices of the photodetector. A first phase difference signal is obtained that indicates the degree to which the phase of the light receiving signal corresponding to a first light receiving device farthest advanced in the radial direction leads the phase of the light receiving signal corresponding to a second light receiving device. A second phase difference signal is obtained that indicates the degree to which the phase of the light receiving signal corresponding to the second light receiving device leads the phase of the light receiving signal corresponding to the first light receiving device. The first and second phase difference signals are integrated and then added to each other to obtain a signal that indicates the direction of movement of the laser spot. The direction of movement of the laser spot is detected according to whether the phase of the direction detecting signal leads or lags the phase of a tracking error signal.